Sirhan Sirhan, the man convicted of murdering Robert F. Kennedy, was stabbed to death in a California jail, according to US media reports.
Authorities said a knife-kick had been taken on Friday afternoon in a jail near San Diego.
A statement from the California Department of Corrections and Rehabilitation said that "officials responded quickly to the attack."
The victim, whose condition is stable, was not mentioned in the statement.
Several US media reports have identified 75-year-old Sirhan as a victim, citing unspecified sources of prosecution.
Sirhan is serving a life sentence in the Richard J. Donovan Penitentiary, where the stab took place.
The alleged attacker, a fellow inmate, was isolated, according to the TMZ, which first reported the attack.
The motive for the attack which was investigated was not revealed by officials.
Who is Sirhan Sirhan?
Sirhan was convicted of killing President Kennedy, whom he shot dead three times at the Ambassador Hotel on June 5, 1968, in Los Angeles.
Kennedy was shot dead in the hotel kitchen shortly after proclaiming victory in California's Democratic presidency.
The New York Senator, brother of former Democratic President John F. Kennedy, died 24 hours later at the hospital.
He was later buried at Arlington Cemetery near his brother John, who was murdered in 1963.
During his trial in 1969, Sirhan was initially sentenced to death. However, three years later, his sentence was commuted to life imprisonment when California briefly suspended capital punishment.
Sirhan, a Palestinian with Jordanian citizenship, claims to have no memory of having shot Kennedy. [19659007IneinemFernsehinterviewsagteSirhanerfühlesichdurchKennedysUnterstützungIsraelsimSechs-dayKriegvon1967betrogen